Self-propelled, walk-behind lawn mowers are typically limited to a speed that is proportional to the speed of an engine that drives the mower and also rotates the mower blade. A throttle controls the speed of the engine, and, if it is desired to slow down the speed at which the mower travels, the engine must be slowed down by control of the throttle, thereby causing the blade to be rotated at a slower speed that may be inadequate for proper cutting.
With modern self-propelled lawn mowers, typically there is a control handle that projects upwardly and rearwardly from the body of the mower. While the angular relationship of the control handle relative to the body is frequently adjustable, once adjusted and in use, the angular relationship is fixed. A throttle control and a drive engagement lever are typically pivotally connected to the control handle at a location spaced toward the lawn mower from that portion of the control handle that is intended to be gripped by the operator for steering of the lawn mower. Thus, if the throttle or the driving engagement lever is to be manipulated, the operator has but one hand to grip the steering portion, making it difficult to disengage the drive or throttle down the mower when one wishes to manipulate the mower around trees, shrubs or other obstructions.
The manipulation of the mower is further complicated in that, in order to meet safety regulations, "dead man" blade controls are now provided. The dead man control is typically a member that is pivotally carried by the control handle and connected by a linkage to a blade engagement mechanism such that the blade is driven when, but only when, the blade control member is grasped by the operator concurrently with grasping of the control handle. Thus, it is necessary to keep at least one hand on the control handle and the blade control member as one maneuvers around the trees, shrubs or other obstructions.
Prior self-propelled, walk-behind lawn mowers can be difficult to control as their take-off is often jerky. In addition, this type of lawn mower tends to "race away" from the operator when going down a hill. When going up a hill, the lawn mower tends to "drag." Once again, in order to adjust the speed of the lawn mower, the operator must remove one hand from the gripping portion and adjust the throttle.
Suggestion has been made in vacuum cleaner prior art to use a drive transmission design for a vacuum cleaner in a lawn mower. These vacuum cleaner transmissions have been intended to improve the performance of vacuum cleaners but, prior to the cleaner of the grandparent application, have met with limited success. While the suggestion has been made, because of adaptability and other problems, lawn mowers have not been made commercially available using any of the prior art vacuum cleaner or similar drive transmissions.
The parent patent application discloses a lawn mower having a drive transmission that was developed from the vacuum cleaner of the grandparent patent application. The parent drive transmission includes a driven member coupled to the engine for constant rotation about a driven axis, an output element axially aligned with the driven member, and a clutch operatively interposed between the driven member and the output element for selectively establishing a drive connection therebetween. A belt is trained around the output element and is also trained around a driven element that is operatively connected to a drive shaft to rotate the drive shaft and thereby wheels connected to it.